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/* libs/opengles/dxt.cpp
**
** Copyright 2007, The Android Open Source Project
**
** Licensed under the Apache License, Version 2.0 (the "License");
** you may not use this file except in compliance with the License.
** You may obtain a copy of the License at
**
** http://www.apache.org/licenses/LICENSE-2.0
**
** Unless required by applicable law or agreed to in writing, software
** distributed under the License is distributed on an "AS IS" BASIS,
** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
** See the License for the specific language governing permissions and
** limitations under the License.
*/
#define TIMING 0
#if TIMING
#include <sys/time.h> // for optimization timing
#include <stdio.h>
#include <stdlib.h>
#endif
#include <GLES/gl.h>
#include <utils/Endian.h>
#include "context.h"
#define TIMING 0
namespace android {
static uint8_t avg23tab[64*64];
static volatile int tables_initialized = 0;
// Definitions below are equivalent to these over the valid range of arguments
// #define div5(x) ((x)/5)
// #define div7(x) ((x)/7)
// Use fixed-point to divide by 5 and 7
// 3277 = 2^14/5 + 1
// 2341 = 2^14/7 + 1
#define div5(x) (((x)*3277) >> 14)
#define div7(x) (((x)*2341) >> 14)
// Table with entry [a << 6 | b] = (2*a + b)/3 for 0 <= a,b < 64
#define avg23(x0,x1) avg23tab[((x0) << 6) | (x1)]
// Extract 5/6/5 RGB
#define red(x) (((x) >> 11) & 0x1f)
#define green(x) (((x) >> 5) & 0x3f)
#define blue(x) ( (x) & 0x1f)
/*
* Convert 5/6/5 RGB (as 3 ints) to 8/8/8
*
* Operation count: 8 <<, 0 &, 5 |
*/
inline static int rgb565SepTo888(int r, int g, int b)
{
return ((((r << 3) | (r >> 2)) << 16) |
(((g << 2) | (g >> 4)) << 8) |
((b << 3) | (b >> 2)));
}
/*
* Convert 5/6/5 RGB (as a single 16-bit word) to 8/8/8
*
* r4r3r2r1 r0g5g4g3 g2g1g0b4 b3b2b1b0 rgb
* r4r3r2 r1r0g5g4 g3g2g1g0 b4b3b2b1 b0 0 0 0 rgb << 3
* r4r3r2r1 r0r4r3r2 g5g4g3g2 g1g0g5g4 b4b3b2b1 b0b4b3b2 desired result
*
* Construct the 24-bit RGB word as:
*
* r4r3r2r1 r0------ -------- -------- -------- -------- (rgb << 8) & 0xf80000
* r4r3r2 -------- -------- -------- -------- (rgb << 3) & 0x070000
* g5g4g3g2 g1g0---- -------- -------- (rgb << 5) & 0x00fc00
* g5g4 -------- -------- (rgb >> 1) & 0x000300
* b4b3b2b1 b0------ (rgb << 3) & 0x0000f8
* b4b3b2 (rgb >> 2) & 0x000007
*
* Operation count: 5 <<, 6 &, 5 | (n.b. rgb >> 3 is used twice)
*/
inline static int rgb565To888(int rgb)
{
int rgb3 = rgb >> 3;
return (((rgb << 8) & 0xf80000) |
( rgb3 & 0x070000) |
((rgb << 5) & 0x00fc00) |
((rgb >> 1) & 0x000300) |
( rgb3 & 0x0000f8) |
((rgb >> 2) & 0x000007));
}
#if __BYTE_ORDER == __BIG_ENDIAN
static uint32_t swap(uint32_t x) {
int b0 = (x >> 24) & 0xff;
int b1 = (x >> 16) & 0xff;
int b2 = (x >> 8) & 0xff;
int b3 = (x ) & 0xff;
return (uint32_t)((b3 << 24) | (b2 << 16) | (b1 << 8) | b0);
}
#endif
static void
init_tables()
{
if (tables_initialized) {
return;
}
for (int i = 0; i < 64; i++) {
for (int j = 0; j < 64; j++) {
int avg = (2*i + j)/3;
avg23tab[(i << 6) | j] = avg;
}
}
asm volatile ("" : : : "memory");
tables_initialized = 1;
}
/*
* Utility to scan a DXT1 compressed texture to determine whether it
* contains a transparent pixel (color0 < color1, code == 3). This
* may be useful if the application lacks information as to whether
* the true format is GL_COMPRESSED_RGB_S3TC_DXT1_EXT or
* GL_COMPRESSED_RGBA_S3TC_DXT1_EXT.
*/
bool
DXT1HasAlpha(const GLvoid *data, int width, int height) {
#if TIMING
struct timeval start_t, end_t;
struct timezone tz;
gettimeofday(&start_t, &tz);
#endif
bool hasAlpha = false;
int xblocks = (width + 3)/4;
int yblocks = (height + 3)/4;
int numblocks = xblocks*yblocks;
uint32_t const *d32 = (uint32_t *)data;
for (int b = 0; b < numblocks; b++) {
uint32_t colors = *d32++;
#if __BYTE_ORDER == __BIG_ENDIAN
colors = swap(colors);
#endif
uint16_t color0 = colors & 0xffff;
uint16_t color1 = colors >> 16;
if (color0 < color1) {
// There's no need to endian-swap within 'bits'
// since we don't care which pixel is the transparent one
uint32_t bits = *d32++;
// Detect if any (odd, even) pair of bits are '11'
// bits: b31 b30 b29 ... b3 b2 b1 b0
// bits >> 1: b31 b31 b30 ... b4 b3 b2 b1
// &: b31 (b31 & b30) (b29 & b28) ... (b2 & b1) (b1 & b0)
// & 0x55..: 0 (b31 & b30) 0 ... 0 (b1 & b0)
if (((bits & (bits >> 1)) & 0x55555555) != 0) {
hasAlpha = true;
goto done;
}
} else {
// Skip 4 bytes
++d32;
}
}
done:
#if TIMING
gettimeofday(&end_t, &tz);
long usec = (end_t.tv_sec - start_t.tv_sec)*1000000 +
(end_t.tv_usec - start_t.tv_usec);
printf("Scanned w=%d h=%d in %ld usec\n", width, height, usec);
#endif
return hasAlpha;
}
static void
decodeDXT1(const GLvoid *data, int width, int height,
void *surface, int stride,
bool hasAlpha)
{
init_tables();
uint32_t const *d32 = (uint32_t *)data;
// Color table for the current block
uint16_t c[4];
c[0] = c[1] = c[2] = c[3] = 0;
// Specified colors from the previous block
uint16_t prev_color0 = 0x0000;
uint16_t prev_color1 = 0x0000;
uint16_t* rowPtr = (uint16_t*)surface;
for (int base_y = 0; base_y < height; base_y += 4, rowPtr += 4*stride) {
uint16_t *blockPtr = rowPtr;
for (int base_x = 0; base_x < width; base_x += 4, blockPtr += 4) {
uint32_t colors = *d32++;
uint32_t bits = *d32++;
#if __BYTE_ORDER == __BIG_ENDIAN
colors = swap(colors);
bits = swap(bits);
#endif
// Raw colors
uint16_t color0 = colors & 0xffff;
uint16_t color1 = colors >> 16;
// If the new block has the same base colors as the
// previous one, we don't need to recompute the color
// table c[]
if (color0 != prev_color0 || color1 != prev_color1) {
// Store raw colors for comparison with next block
prev_color0 = color0;
prev_color1 = color1;
int r0 = red(color0);
int g0 = green(color0);
int b0 = blue(color0);
int r1 = red(color1);
int g1 = green(color1);
int b1 = blue(color1);
if (hasAlpha) {
c[0] = (r0 << 11) | ((g0 >> 1) << 6) | (b0 << 1) | 0x1;
c[1] = (r1 << 11) | ((g1 >> 1) << 6) | (b1 << 1) | 0x1;
} else {
c[0] = color0;
c[1] = color1;
}
int r2, g2, b2, r3, g3, b3, a3;
int bbits = bits >> 1;
bool has2 = ((bbits & ~bits) & 0x55555555) != 0;
bool has3 = ((bbits & bits) & 0x55555555) != 0;
if (has2 || has3) {
if (color0 > color1) {
r2 = avg23(r0, r1);
g2 = avg23(g0, g1);
b2 = avg23(b0, b1);
r3 = avg23(r1, r0);
g3 = avg23(g1, g0);
b3 = avg23(b1, b0);
a3 = 1;
} else {
r2 = (r0 + r1) >> 1;
g2 = (g0 + g1) >> 1;
b2 = (b0 + b1) >> 1;
r3 = g3 = b3 = a3 = 0;
}
if (hasAlpha) {
c[2] = (r2 << 11) | ((g2 >> 1) << 6) |
(b2 << 1) | 0x1;
c[3] = (r3 << 11) | ((g3 >> 1) << 6) |
(b3 << 1) | a3;
} else {
c[2] = (r2 << 11) | (g2 << 5) | b2;
c[3] = (r3 << 11) | (g3 << 5) | b3;
}
}
}
uint16_t* blockRowPtr = blockPtr;
for (int y = 0; y < 4; y++, blockRowPtr += stride) {
// Don't process rows past the botom
if (base_y + y >= height) {
break;
}
int w = min(width - base_x, 4);
for (int x = 0; x < w; x++) {
int code = bits & 0x3;
bits >>= 2;
blockRowPtr[x] = c[code];
}
}
}
}
}
// Output data as internalformat=GL_RGBA, type=GL_UNSIGNED_BYTE
static void
decodeDXT3(const GLvoid *data, int width, int height,
void *surface, int stride)
{
init_tables();
uint32_t const *d32 = (uint32_t *)data;
// Specified colors from the previous block
uint16_t prev_color0 = 0x0000;
uint16_t prev_color1 = 0x0000;
// Color table for the current block
uint32_t c[4];
c[0] = c[1] = c[2] = c[3] = 0;
uint32_t* rowPtr = (uint32_t*)surface;
for (int base_y = 0; base_y < height; base_y += 4, rowPtr += 4*stride) {
uint32_t *blockPtr = rowPtr;
for (int base_x = 0; base_x < width; base_x += 4, blockPtr += 4) {
#if __BYTE_ORDER == __BIG_ENDIAN
uint32_t alphahi = *d32++;
uint32_t alphalo = *d32++;
alphahi = swap(alphahi);
alphalo = swap(alphalo);
#else
uint32_t alphalo = *d32++;
uint32_t alphahi = *d32++;
#endif
uint32_t colors = *d32++;
uint32_t bits = *d32++;
#if __BYTE_ORDER == __BIG_ENDIAN
colors = swap(colors);
bits = swap(bits);
#endif
uint64_t alpha = ((uint64_t)alphahi << 32) | alphalo;
// Raw colors
uint16_t color0 = colors & 0xffff;
uint16_t color1 = colors >> 16;
// If the new block has the same base colors as the
// previous one, we don't need to recompute the color
// table c[]
if (color0 != prev_color0 || color1 != prev_color1) {
// Store raw colors for comparison with next block
prev_color0 = color0;
prev_color1 = color1;
int bbits = bits >> 1;
bool has2 = ((bbits & ~bits) & 0x55555555) != 0;
bool has3 = ((bbits & bits) & 0x55555555) != 0;
if (has2 || has3) {
int r0 = red(color0);
int g0 = green(color0);
int b0 = blue(color0);
int r1 = red(color1);
int g1 = green(color1);
int b1 = blue(color1);
int r2 = avg23(r0, r1);
int g2 = avg23(g0, g1);
int b2 = avg23(b0, b1);
int r3 = avg23(r1, r0);
int g3 = avg23(g1, g0);
int b3 = avg23(b1, b0);
c[0] = rgb565SepTo888(r0, g0, b0);
c[1] = rgb565SepTo888(r1, g1, b1);
c[2] = rgb565SepTo888(r2, g2, b2);
c[3] = rgb565SepTo888(r3, g3, b3);
} else {
// Convert to 8 bits
c[0] = rgb565To888(color0);
c[1] = rgb565To888(color1);
}
}
uint32_t* blockRowPtr = blockPtr;
for (int y = 0; y < 4; y++, blockRowPtr += stride) {
// Don't process rows past the botom
if (base_y + y >= height) {
break;
}
int w = min(width - base_x, 4);
for (int x = 0; x < w; x++) {
int a = alpha & 0xf;
alpha >>= 4;
int code = bits & 0x3;
bits >>= 2;
blockRowPtr[x] = c[code] | (a << 28) | (a << 24);
}
}
}
}
}
// Output data as internalformat=GL_RGBA, type=GL_UNSIGNED_BYTE
static void
decodeDXT5(const GLvoid *data, int width, int height,
void *surface, int stride)
{
init_tables();
uint32_t const *d32 = (uint32_t *)data;
// Specified alphas from the previous block
uint8_t prev_alpha0 = 0x00;
uint8_t prev_alpha1 = 0x00;
// Specified colors from the previous block
uint16_t prev_color0 = 0x0000;
uint16_t prev_color1 = 0x0000;
// Alpha table for the current block
uint8_t a[8];
a[0] = a[1] = a[2] = a[3] = a[4] = a[5] = a[6] = a[7] = 0;
// Color table for the current block
uint32_t c[4];
c[0] = c[1] = c[2] = c[3] = 0;
int good_a5 = 0;
int bad_a5 = 0;
int good_a6 = 0;
int bad_a6 = 0;
int good_a7 = 0;
int bad_a7 = 0;
uint32_t* rowPtr = (uint32_t*)surface;
for (int base_y = 0; base_y < height; base_y += 4, rowPtr += 4*stride) {
uint32_t *blockPtr = rowPtr;
for (int base_x = 0; base_x < width; base_x += 4, blockPtr += 4) {
#if __BYTE_ORDER == __BIG_ENDIAN
uint32_t alphahi = *d32++;
uint32_t alphalo = *d32++;
alphahi = swap(alphahi);
alphalo = swap(alphalo);
#else
uint32_t alphalo = *d32++;
uint32_t alphahi = *d32++;
#endif
uint32_t colors = *d32++;
uint32_t bits = *d32++;
#if __BYTE_ORDER == __BIG_ENDIANx
colors = swap(colors);
bits = swap(bits);
#endif
uint64_t alpha = ((uint64_t)alphahi << 32) | alphalo;
uint64_t alpha0 = alpha & 0xff;
alpha >>= 8;
uint64_t alpha1 = alpha & 0xff;
alpha >>= 8;
if (alpha0 != prev_alpha0 || alpha1 != prev_alpha1) {
prev_alpha0 = alpha0;
prev_alpha1 = alpha1;
a[0] = alpha0;
a[1] = alpha1;
int a01 = alpha0 + alpha1 - 1;
if (alpha0 > alpha1) {
a[2] = div7(6*alpha0 + alpha1);
a[4] = div7(4*alpha0 + 3*alpha1);
a[6] = div7(2*alpha0 + 5*alpha1);
// Use symmetry to derive half of the values
// A few values will be off by 1 (~.5%)
// Alternate which values are computed directly
// and which are derived to try to reduce bias
a[3] = a01 - a[6];
a[5] = a01 - a[4];
a[7] = a01 - a[2];
} else {
a[2] = div5(4*alpha0 + alpha1);
a[4] = div5(2*alpha0 + 3*alpha1);
a[3] = a01 - a[4];
a[5] = a01 - a[2];
a[6] = 0x00;
a[7] = 0xff;
}
}
// Raw colors
uint16_t color0 = colors & 0xffff;
uint16_t color1 = colors >> 16;
// If the new block has the same base colors as the
// previous one, we don't need to recompute the color
// table c[]
if (color0 != prev_color0 || color1 != prev_color1) {
// Store raw colors for comparison with next block
prev_color0 = color0;
prev_color1 = color1;
int bbits = bits >> 1;
bool has2 = ((bbits & ~bits) & 0x55555555) != 0;
bool has3 = ((bbits & bits) & 0x55555555) != 0;
if (has2 || has3) {
int r0 = red(color0);
int g0 = green(color0);
int b0 = blue(color0);
int r1 = red(color1);
int g1 = green(color1);
int b1 = blue(color1);
int r2 = avg23(r0, r1);
int g2 = avg23(g0, g1);
int b2 = avg23(b0, b1);
int r3 = avg23(r1, r0);
int g3 = avg23(g1, g0);
int b3 = avg23(b1, b0);
c[0] = rgb565SepTo888(r0, g0, b0);
c[1] = rgb565SepTo888(r1, g1, b1);
c[2] = rgb565SepTo888(r2, g2, b2);
c[3] = rgb565SepTo888(r3, g3, b3);
} else {
// Convert to 8 bits
c[0] = rgb565To888(color0);
c[1] = rgb565To888(color1);
}
}
uint32_t* blockRowPtr = blockPtr;
for (int y = 0; y < 4; y++, blockRowPtr += stride) {
// Don't process rows past the botom
if (base_y + y >= height) {
break;
}
int w = min(width - base_x, 4);
for (int x = 0; x < w; x++) {
int acode = alpha & 0x7;
alpha >>= 3;
int code = bits & 0x3;
bits >>= 2;
blockRowPtr[x] = c[code] | (a[acode] << 24);
}
}
}
}
}
/*
* Decode a DXT-compressed texture into memory. DXT textures consist of
* a series of 4x4 pixel blocks in left-to-right, top-down order.
* The number of blocks is given by ceil(width/4)*ceil(height/4).
*
* 'data' points to the texture data. 'width' and 'height' indicate the
* dimensions of the texture. We assume width and height are >= 0 but
* do not require them to be powers of 2 or divisible by any factor.
*
* The output is written to 'surface' with each scanline separated by
* 'stride' 2- or 4-byte words.
*
* 'format' indicates the type of compression and must be one of the following:
*
* GL_COMPRESSED_RGB_S3TC_DXT1_EXT:
* The output is written as 5/6/5 opaque RGB (16 bit words).
* 8 bytes are read from 'data' for each block.
*
* GL_COMPRESSED_RGBA_S3TC_DXT1_EXT
* The output is written as 5/5/5/1 RGBA (16 bit words)
* 8 bytes are read from 'data' for each block.
*
* GL_COMPRESSED_RGBA_S3TC_DXT3_EXT
* GL_COMPRESSED_RGBA_S3TC_DXT5_EXT
* The output is written as 8/8/8/8 ARGB (32 bit words)
* 16 bytes are read from 'data' for each block.
*/
void
decodeDXT(const GLvoid *data, int width, int height,
void *surface, int stride, int format)
{
#if TIMING
struct timeval start_t, end_t;
struct timezone tz;
gettimeofday(&start_t, &tz);
#endif
switch (format) {
case GL_COMPRESSED_RGB_S3TC_DXT1_EXT:
decodeDXT1(data, width, height, surface, stride, false);
break;
case GL_COMPRESSED_RGBA_S3TC_DXT1_EXT:
decodeDXT1(data, width, height, surface, stride, true);
break;
case GL_COMPRESSED_RGBA_S3TC_DXT3_EXT:
decodeDXT3(data, width, height, surface, stride);
break;
case GL_COMPRESSED_RGBA_S3TC_DXT5_EXT:
decodeDXT5(data, width, height, surface, stride);
break;
}
#if TIMING
gettimeofday(&end_t, &tz);
long usec = (end_t.tv_sec - start_t.tv_sec)*1000000 +
(end_t.tv_usec - start_t.tv_usec);
printf("Loaded w=%d h=%d in %ld usec\n", width, height, usec);
#endif
}
} // namespace android
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